CN1242565C - Method and device for power amplification in base station - Google Patents

Abstract

The invention relates to a terrestrial cellular radio communication network (101) comprising at least a first base station (BS1), wherein a common set of multi-carrier power amplifiers (409) and 412) is used for amplifying radio signals transmitted by the first base station (BS1) in different cells. The present invention enables a reduction in the total maximum output power that needs to be supported by a first base station (BS1) when downlink power control functions, such as power control or discontinuous transmission, and/or adaptive channel allocation, are applied to the cell served by the first base station (BS 1).

Description

Method and device for power amplification in base station

                            

The present invention relates to methods and devices related to wireless communication systems. More specifically, the present invention relates to a method for transmitting wireless signals in a highly flexible and efficient manner by using power amplification resources of a base station in a terrestrial cellular wireless communication network. The invention includes a terrestrial wireless communication network comprising the means necessary for carrying out the method. The invention also includes a method for calculating the size of the power amplification resources of the base station.

Related technical description

In terrestrial wireless communication systems, a major component of base station cost is related to the power amplification of the radio signals transmitted by the base station.

Traditionally, base stations are equipped with so-called single-carrier power amplifiers (SCPA), each SCPA amplifies a single radio frequency carrier, and is designed such that it can deliver enough power to support communication with mobile stations located at the border of the cell,

Another way of designing power amplification components of base stations, which is becoming more and more common, is to equip base stations with so-called multi-carrier power amplifiers (MCPAs), where each MCPA is capable of amplifying a wireless signal comprising several radio frequency carriers. Typically, a base station serving a single cell is equipped with one MCPA or a group of MCPAs operating in parallel, while a base station serving multiple (sector) cells is equipped with one MCPA per cell or a group of MCPAs operating in parallel . There are several advantages where the base station uses MCPA rather than SCPA. One advantage obtained when using MCPA is that it is possible to benefit from functions such as downlink power control (DPC) and discontinuous transmission (DTX), which give Statistical reduction in total output power. Use of the DPC function is estimated to result in a statistical reduction of about 4-6 dB in required output power, while use of the DTX function is estimated to result in a reduction of about 3-4 dB, for a total reduction of about 10 times. This means that an MCPA designed to support a certain number of radio frequency carriers can be designed to deliver much less output power than would be required in total if multiple SCPAs supported the same number of carriers.

However, in order to achieve the overall statistical reduction given by the DPC and DTX functions, the number of radio frequency carriers must be large.

US Patent 5,854,611 discloses a base station serving a single cell, such as an Advanced Mobile Phone Service (AMPS) base station, where multiple narrow antenna beams (eg 10 beams) are used to provide radio coverage in the cell. The base station includes a first power sharing network coupled to a plurality of linear power amplifiers coupled to a second power sharing network. The first power sharing network equally distributes the received input signal from one of its input ports to a plurality of linear power amplifiers coupled to the sharing network at substantially equal power levels and mutually in phase Jagged arrangement. A linear amplifier independently amplifies each respective output signal from the first power network. The second power sharing network receives the phase staggered amplified signals and provides an average power having a power level relative to the combination of the phase staggered amplified input signals input to the second power sharing network level output signal. The output signal from the second power sharing network is then radiated in one of the narrow antenna beams. The base station and antenna system disclosed in US Pat. No. 5,854,611 provides the advantages associated with the use of narrow antenna beams while avoiding the need for inefficient dedicated power amplifiers for each individual narrow antenna beam.

US Patent 4,618,813 discloses a power amplification device in which signals to be provided individually to multiple outputs and fed to multiple inputs will share the sum of the output power capacities of the multiple amplifiers. This patent specification briefly discusses the use of power amplification devices in multi-beam satellite antenna systems.

Summary of Invention

The problem addressed by the present invention is how to provide a low-cost and flexible method of implementing radio signal power amplification in a base station of a terrestrial radio communication network.

The problem is basically solved by a method and a device in which a common set of multicarrier power amplifiers is used to amplify radio signals transmitted by base stations in different cells.

More specifically, the problem is solved in the following manner. A first set of low power wireless signals comprising at least first and second wireless signals is generated. A first radio signal is generated such that the signal contains a radio carrier component having a frequency that can be assigned to a first cell of the cellular radio communication network. A second radio signal is generated such that the signal contains a radio carrier component having a frequency that can be assigned to a second cell of the cellular radio communication network. A second set of amplified wireless signals corresponding to the first set of wireless signals is generated by using the common set of multicarrier power amplifiers to amplify the first set of wireless signals. A second set of amplified radio signals is radiated in the form of associated antenna beams, wherein the amplified radio signals corresponding to the first radio signals are radiated in the form of antenna beams associated with the first cell, and the amplified radio signals corresponding to the second The amplified radio signal of the two radio signals is radiated in the form of an antenna beam associated with the second cell.

A general object of the present invention is to provide a low-cost and flexible method of power amplification of radio signals in a base station of a terrestrial radio communication network.

Another object of the present invention is to reduce the maximum total output power that the base station needs to deliver in order to serve a certain number of wireless carriers, or to serve more wireless carriers with a given maximum total output power. carrier.

Yet another object is to enable reallocation of output power between different cells served by one base station.

A further object is to enable the output power available in the cell, and the number of radio frequency carrier frequencies, to be adjusted in response to changing capacity requirements in the cell.

The overall advantage afforded by the present invention is that it provides a low-cost and flexible method of radio signal power amplification in base stations of terrestrial radio communication networks.

A more specific advantage afforded by the invention is that the total maximum output power required by a base station in order to serve a certain number of radio carriers can be reduced. This means that the equipment cost, power consumption, volume and weight of the base station can be reduced.

A further advantage afforded by the invention is that the output power can be redistributed between different cells served by one base station.

A further advantage afforded by the invention is that the output power and the number of radio frequency carrier frequencies available in a cell can be adjusted according to changing capacity requirements in the cell.

The present invention will now be described in more detail with reference to exemplary embodiments of the invention and with reference to the accompanying drawings.

Brief description of attached drawings

Figure 1 is a schematic diagram of components of a terrestrial wireless communication network.

FIG. 2 is a diagram showing a cell pattern of "4/12" for frequency reuse.

Figure 3 is a graph showing the statistical reduction in total maximum output power required due to use of the power reduction function in the downlink.

FIG. 4 is a block diagram showing details of the first base station and the mobile services switching center of FIG. 1 according to the first embodiment of the present invention.

5A-5C are flowcharts showing a method according to a first embodiment of the present invention applied to the network of FIG. 1. FIG.

Fig. 6 is a block diagram showing a 180 degree 3dB hybrid coupler.

Fig. 7 is a block diagram showing a power amplifying device in the first base station.

Fig. 8 is a flowchart showing a method for dimensioning a power amplification unit in a first base station.

Figure 9 is a graph showing the cumulative distribution function of required output power.

Detailed description of the embodiment

Figure 1 shows components of a radio communication system 100, which comprises a terrestrial cellular radio communication network 101 (hereinafter referred to as cellular network 101) and a set of mobile stations MS1-MS4. In the wireless communication system 100 shown in FIG. 1, the communication between the cellular network 101 and the mobile stations MS1-MS4 is based on the TIA/EIA IS-136 air interface specification. The cellular network 101 comprises a mobile services switching center MSC1 and base stations BS1-BS3 connected to the mobile services switching center MSC1. The base stations BS1-BS3 provide radio coverage in the geographical area served by the mobile services switching center MSC1. The mobile services switching center MSC1 is responsible for switching calls to and from mobile stations MS1-MS4 located in the geographical area served by the mobile services switching center MSC1. It should be noted that Figure 1 includes only elements considered necessary to illustrate the invention, and that a typical cellular network includes several mobile services switching centers, a large number of base stations, and other types of nodes, such as home location registers.

Frequency reuse is a key concept in cellular networks. This is a technique used to allocate groups of frequencies for use by areas of limited geographic coverage, known as cells. Cells containing the same frequency group are geographically separated to allow callers in different cells to use the same frequency simultaneously without interfering with each other. Figure 1 shows how the geographical area served by the mobile services switching center MSC1 is divided into five cells C1-C5. In each cell C1-C5 radio coverage is provided by one of the base stations BS1-BS3 respectively. Base stations BS2 and BS3 provide wireless coverage in cells C4 and C5 respectively, that is, base stations BS2 and BS3 provide wireless coverage in one cell respectively, while base station BS1 (referred to as the first base station BS1 below) provides wireless coverage in three cells. Radio coverage in the cells C1-C3, ie the base station BS1 provides radio coverage in a plurality of cells. The transmission of radio signals from any of the base stations BS1-BS3 to the mobile stations MS1-MS4 is said to take place in the downlink direction, while the transmission of radio signals from any of the mobile stations MS1-MS4 to the base station BS1-MS4 is said to take place in the downlink direction. The transmission of radio signals by any one of the base stations in BS3 is said to take place in the uplink direction.

Frequency planning is a process used to assign individual radio frequencies to cells within a cellular network. Most of the current frequency planning is done in advance, that is, a fixed frequency plan is "hardwired" fixed by each cellular network operator. This is known as Fixed Channel Assignment (FCA). Figure 2 shows an example of an FCA scheme: it is in the form of a so-called "4/12" cell pattern for frequency reuse. The "4/12" cell pattern is applied to the cellular network 101 of Figure 1. In this multiplexing scheme, the total frequency band allocated to the cellular network 101 is divided into 12 frequency groups FA1-FA3, FB1-FB3, FC1- FC3 and FD1-FD3. Each cell is assigned a frequency group according to the pattern shown in FIG. 2 , for example, cells C1-C5 are assigned frequency groups FA1-FA3, FB2 and FD1, as shown in FIG. 1 .

Adaptive Channel Allocation (ACA) is a method for dynamically allocating frequencies through a cellular network to maximize network capacity. Under the ACA scheme, more frequencies are allocated from lighter loaded cells to busy cells. Additionally, channels may be allocated such that all links are of satisfactory quality. A number of different ACA schemes have been proposed, such as those proposed in International Patent Application WO 97/32444 and US Patent 5,491,837. It may be noted that there is a difference between allocating a frequency for use in a cell (ie making the frequency available in the cell) and actually carrying out the transmission of a radio frequency carrier by using the allocated frequency. The two steps of allocating a frequency and actually making that frequency available for wireless transmission, however, can occur substantially simultaneously.

A major part of the cost of each base station BS1-BS3 in the cellular network 101 is related to the power amplification of the radio signals transmitted by the base stations. The cost involved in the power amplification equipment is actually proportional to the total maximum output power that the base station is designed to deliver. Therefore, it is important to utilize the output power available in the base station as efficiently as possible and to minimize the total maximum output power required. Since the base station is designed to deliver less total maximum output power, not only equipment cost but also power consumption, size and weight can be reduced.

There are various known power reduction functions, such as power control and intermittent transmission (alternatively referred to as voice-steered transmission), which, when applied to the RF carrier, result in a reduction in the average RF carrier signal power. Small. These power reduction functions have been used to reduce the level of interference in cellular networks, as well as to extend the runtime of mobile stations by conserving battery power. When such power reduction functions are applied to the radio frequency carriers transmitted by the base station in the downlink direction, they result in a statistical reduction in the total output power that the base station needs to deliver in order to be able to support a certain number of radio frequency carriers. The required statistical reduction of the total output power depends on that if the output power is set individually for each carrier on each time slot, then this is extremely unlikely to occur if there is a sufficient number of radio frequency carriers. A worst case scenario where all RF carriers simultaneously require maximum output power. Since the worst case has a very low probability, the base station need not be designed to provide enough output power to handle the worst case. Conversely, the base station may be designed to provide sufficient output power to ensure that there is an acceptable probability, ie a sufficiently low, but not zero probability, that a situation occurs in which the base station cannot provide sufficient output power.

Figure 3 is a graph showing the required total output power P _RED1 (in dB A plot of the statistically reduced estimate of .

As shown in Figure 3, the use of the downlink control function is estimated to result in a statistical reduction of about 4 dB in the required output power, provided that the number of radio frequency carriers is sufficiently high. Thus, a power amplifier designed to support 15 radio frequency carriers can be designed such that each radio frequency carrier delivers much less output power than a power amplifier designed to support 5 radio frequency carriers.

The present invention provides a way to further reduce the total maximum output power required to be delivered by the base station in the case of several radio frequency carriers in a cell in order to fully benefit from the utilization of the power reduction function in the downlink direction.

It is often the case in a terrestrial cellular radio communication network like the cellular network 101 of Figure 1 that the capacity requirement fluctuates from cell to cell during a given time interval. If, in an example situation, cell C1 basically covers a sports center, cell C2 covers a shopping area, and cell C3 covers an office area, the capacity demand in cells C1-C3 can be expected to exhibit significant fluctuations. Also, at a given point in time, the capacity demand will not be at its peak in all three cells at the same time. The capacity demand in cell C1 is high only when there is some major event in the sports center (typically, several nights of the week). Capacity demand in cell C2 is high only during shopping hours (eg lunchtime and earlier in the evening on weekdays). In cell C3 the capacity demand is only high during office hours. By applying some kind of adaptive small allocation scheme, the cellular network 101 is able to adjust the set of frequencies allocated to each cell C1-C3 according to the changing capacity requirements in the cell. However, if cell C1 is allocated one or several additional frequencies due to extra capacity requirements during football matches, the first base station BS1 must be able to deliver sufficient output power in cell C1 to support downlink transmission. Therefore, in order to benefit from the possibility offered by the ACA scheme of allocating additional frequencies in cell C1 to support additional capacity requirements, the first base station BS1 needs to be designed with spare output power capacity in cell C1 , this spare capacity is rarely utilized.

The present invention provides a solution to the problem of enabling the first base station BS1 to provide sufficient output power in the cell C1 to support the allocation of additional frequencies to the cell C1 without the need for the first base station BS1 to be designed in Cell C1 has idle output power capacity with insufficient utilization.

The basic principle of the invention is to use a common set of multicarrier amplifiers to amplify radio signals transmitted by a base station in different cells of a terrestrial cellular network.

The basic principles of the invention can be applied to different embodiments of the invention in order to achieve a further statistical reduction of the required total maximum output power of the base station when the downlink power reduction function is used, and and/or avoid the need to design base stations with spare output power capacity in cells to support allocation of additional frequencies using adaptive channel allocation schemes.

Using a common set of multicarrier power amplifiers serving more than one cell instead of a single set of multicarrier power amplifiers serving each individual cell means that the common set of multicarrier power amplifiers is compared to each individual set of multicarrier power amplifiers In terms of the number of radio frequency carriers handled by a multicarrier power amplifier, an increased number of radio frequency carriers can be processed. Therefore, as discussed in connection with FIG. 3, the use of a common set of multicarrier power amplifiers, combined with the use of downlink power reduction functions such as downlink power control or intermittently transmitting, can result in the required reduction of the total maximum output power.

Using a common set of multicarrier power amplifiers to serve more than one cell also enables the base station to distribute varying amounts of total output power produced by the common set of multicarrier power amplifiers among different cells. Therefore, as long as the total power requirement in all cells does not exceed the maximum output power that can be produced by a common set of multicarrier power amplifiers, it is possible to allocate output power to a cell to support the additional frequencies assigned to that cell.

An exemplary first embodiment of the present invention as applied to the terrestrial cellular radio communication network 101 shown in FIG. 1 will now be described with reference to FIGS. 4 to 7 .

Figure 4 shows more details of the first base station BS1 and the mobile services switching center MSC1 according to a first embodiment of the invention.

The first base station BS1 includes a wireless signal generating device 401 , a power amplifying unit 402 and an antenna system 403 .

The radio signal generating means comprises a digital baseband unit 404 which is connected to three multicarrier transceivers 405-407.

The power amplification unit 402 includes a power sharing network 408 having a plurality of input ports 420-423 and output ports 424-427, a common set of multi-carrier power amplifiers 409-412 (each power amplifier having an input and an output) and also including a reverse power sharing network 413 having a plurality of input ports 428-431 and output ports 432-435. Each amplifier 409-412 is connected by its input port to one of the output ports 424-427 of the power sharing network 408, and by its output port to one of the input ports 428-431 of the reverse power sharing network 413 .

The antenna system 403 includes a first antenna 414 , a second antenna 415 and a third antenna 416 . Each of the antennas 414-416 is associated with a different one of the three cells C1-C3 and provides antenna beams 417-419 for covering the associated cell.

The first base station BS1 also comprises one or several control processors (not shown in FIG. 4 ) for controlling the general operation of the first base station BS1 and handling communications with the mobile services switching center MSC1.

The mobile services switching center MSC1 comprises one or several control processors 440 for executing program instructions stored in one or several memory units 441 .

The first base station BS1 and the mobile services switching center MSC1 communicate with each other using optical fiber or wireless links.

Fig. 5A shows part of a method for transmitting wireless signals in a cellular network 101 according to an exemplary first embodiment of the present invention.

In step 501 , a first group of low-power wireless signals S11 - S13 is generated by the wireless signal generating device 401 . The first group of low-power wireless signals S11-S13 includes a first wireless signal S11, a second wireless signal S12, and a third wireless signal S13. A first signal S11 associated with the first cell C1 is generated such that it contains a radio frequency carrier component having a radio frequency carrier allocated for the first cell C1. Likewise, a second signal S12 associated with the second cell C2 is generated such that it contains a radio frequency carrier component having been allocated for the second cell C2, and a third signal S13 associated with the third cell C3 is generated such that It contains components with radio frequency carriers allocated for the third cell C3.

The baseband unit 404 receives instructions from the mobile services switching center MSC1 as to which radio frequency carrier components should be included in each of the three signals S11-S13, and generates three digital signals corresponding to said signals S11-S13 baseband signal. The digital signals are transmitted to three multicarrier transceivers 405-407, which generate three signals S11-S13 by performing digital-to-analog conversion and radio-frequency conversion of the corresponding digital baseband signals.

Steps 502-504 generate a second group of amplified wireless signals S21-S23 corresponding to the first group of wireless signals S11-S13 by amplifying the first group of wireless signals S11-S13 in the power amplifying unit 402, that is, the second group of wireless The signals S21-S23 comprise an amplified version of each of the signals in the first set of radio signals S11-S13.

At step 502, a third set of wireless signals S31-S34 is provided by the power sharing network 408 at its output ports 424-427. The power sharing network 408 receives the first set of wireless signals S11-S13 at its input ports 420-422, and distributes a portion of each of the first set of wireless signals S11-S13 to each of its output ports 424- 427. Each of the first set of radio signals S11-S13 is distributed to each of the output ports 424-427 in shares having approximately equal power levels and being staggered in phase. Thus, each signal S31-S34 in the third set of radio signals will contain an equal portion of the first radio signal S11. However, the parts of the first radio signal S11 in the signals S31 and S32 are mutually shifted in phase.

In step 503, a fourth set of radio signals S41-S44 is provided by amplifying each signal of the third set of radio signals S31-S34 in one amplifier of the common set of multi-carrier power amplifiers 409-412.

At step 504, the second set of wireless signals S21-S23 is provided by the reverse power sharing network 413 at its output ports 432-434. The reverse power sharing network 413 performs the reverse operation of the power sharing network 408 on the fourth set of wireless signals S41-S44. Accordingly, the reverse power sharing network 413 provides the signal S21 by recombining the content of each signal in the third set S31-S34 originating from the first radio signal S11, which corresponds to the second set of radio signals in the second set S11. A signal of signal S11.

In step 505, a second group of radio signals S21-S23 corresponding to the first group of radio signals S11-S13 is radiated in the form of respective associated antenna beams 417-419, that is, signal S21 (which is a signal corresponding to the first radio signal The amplified wireless signal of S11) is radiated by the first antenna 414 in the form of its antenna beam 417, and the signal S22 (which is the amplified wireless signal corresponding to the second wireless signal S12) is radiated by the second antenna 415 with its antenna The form of the beam 418 is radiated, and the signal S23 , which is an amplified radio signal corresponding to the third radio signal S13 , is radiated by the third antenna 416 in the form of its antenna beam 419 .

6 and 7 give detailed examples on how the power amplifying unit 402 of FIG. 4 can be implemented.

FIG. 6 shows a 180 degree 3dB hybrid coupler 601 . If the input signals added to the hybrid coupler 601 are S61 and S62, the output signals S63 and S64 are:

S63＝(1/√2)*(S61-S62) (1)

S64＝(1/√2)*(S61+S62) (2)

Figure 7 shows how the power sharing network 408 and the reverse power sharing network 413 can be designed as a so called Buter matrix using 180 degree 3dB hybrid couplers.

As can be seen from Figures 4 and 7, the power sharing network 408 has four input ports 420-423, while only three of these input ports 420-422 are used to receive signals in the first set of wireless signals S11-S13.

The main reason for designing the power sharing network 408 and the reverse power sharing network 413 as a Butter matrix with four input ports and four output ports is to have 2n input ports and output ports (for example, 2, 4, 8, or 16 ports) suffers less loss than a Butter matrix with any other number of ports.

In FIGS. 4 and 7 , the power sharing network input port 423 is connected to ground, while the reverse power sharing network output port 435 is connected to a monitor 436 . The monitor 436 verifies that no signal is received at the output port 435, ie the output port 435 is at ground level. If a signal other than ground is actually received by the monitor at the output port 435, this is indicative of a fault somewhere in the power amplification unit 402, and the monitor can provide an error indication to operations and maintenance personnel.

The cellular network 101 applies power control to the transmissions in the downlink direction of all cells C1-C5. Applying power control in the downlink direction means that the transmit power in a time slot on a radio frequency carrier in the downlink direction is adjusted to the actual power required for the radio signal to reach the mobile station with sufficient signal strength . In TIA/EIA-136-131-A "Digital Traffic Channel Layer 1", it is specified that one fast power control (FPC) bit is used for both uplink and downlink directions. The mobile station measures the received signal quality and requests the first base station to increase or decrease the transmission power by setting the FPC bit to 1 or 0 in its transmission in the corresponding time slot in the uplink direction. The first base station BS1 synthesizes the received increase/decrease requests in several consecutive FPC bits in order to determine whether the downlink transmit power should be adjusted, so the mobile station can request the first base station BS1 to maintain current output power.

The first base station BS1 is designed to benefit from the previously discussed statistical reduction in required output power due to the application of power control in the downlink direction. For example, the first base station BS1 can be designed to support simultaneous transmission of five radio frequency carriers in each cell C1-C3, ie, the power amplifying unit 402 is designed to deliver a total maximum output power supporting simultaneous transmission of 15 radio frequency carriers. The antenna feed typically needs to feed 11 watts for downlink transmission of a single radio frequency carrier. Thus, without any power reduction functions such as downlink power control, the power amplification unit must be designed to deliver a total maximum output power of about 165 watts. However, due to the use of downlink power control (which can achieve a statistical reduction of about 3.9 dB or about 2.5 times the required output power for 15 RF carriers), it is sufficient for the power amplification unit 402 to be designed to deliver 66 watts .

As a comparison, a base station designed to support simultaneous transmission of five RF carriers in three cells, with separate power amplification units for each cell, would also Must be designed to deliver a total maximum output power of approximately 165 watts. Using downlink power control in each cell means that the required output power of each separate power amplification unit is only statistically reduced by about 2dB or about 1.6 times, and the total maximum output power required is About 103 watts.

Fig. 8 shows in a more general way the method for sizing the power amplification unit 402, ie the method for selecting its maximum output power.

In step 801, the total output power PREQ required by the power amplifying unit 402 is determined for simultaneous transmission of up to a specified maximum number NMAX of radio frequency carriers in the cell groups C1-C3 relying on the power amplifying unit 402 to perform power amplification statistical distribution. In this particular case, the power amplification unit 402 performs power amplification for all radio frequency carriers transmitted by the first base station BS1 in the three cells C1-C3 served by the first base station BS1, i.e. the power amplification unit 402 Need to be able to support a maximum of 15 RF carriers.

As an example, Fig. 9 shows the cumulative distribution function of the total maximum output power P _REQ required by the power amplifying unit 402 when the first base station BS1 operates under traffic conditions causing a blocking probability of 1% using up to 15 radio frequency carriers 901. Along the horizontal axis, the required total output power P _REQ is expressed in terms of how much the total output power is reduced compared to the total output power corresponding to the maximum transmit power of 15 carriers (ie 165 watts). It should be noted that the first base station BS1 operates with a blocking probability of up to 1% only during busy hours.

In step 802 , the power amplifying unit 420 is sized according to the statistical distribution determined in step 801 . The power amplification unit 402 is dimensioned such that it can deliver the total maximum output power that the power amplification unit 402 cannot adequately provide for the simultaneous transmission of a specified maximum number of radio frequency carriers. Acceptable non-zero probability of output power. In this particular case, when the first base station BS1 is operating under traffic conditions causing a blocking probability of 1%, a 5% probability that the power amplification unit 402 cannot provide sufficient output power is considered acceptable, so, According to the cumulative distribution function 901 on FIG. 9, the power amplification unit 402 is designed to deliver a total maximum output power of 66 watts, ie, 3.9 dB less than 165 watts.

Furthermore, the cellular network 101 utilizes an adaptive channel allocation scheme which allows the set of frequencies allocated for each individual cell C1-C3 to be adjusted to accommodate changes in capacity requirements. The channel allocation scheme used in the cellular network 101 of FIG. 1 is based on the fixed channel allocation scheme according to FIG. The capacity demand of the cell is used. Thus, at any given moment, the set of frequencies allocated to a cell includes the basic set of frequencies allocated in accordance with a substantially fixed channel allocation scheme (excluding borrowed frequencies for use by other cells), and may also include Additional frequency groups borrowed from the cell.

5B and 5C show an adaptive channel allocation scheme used in the cellular network 101 according to the first exemplary embodiment of the present invention.

In step 510 of FIG. 5B, a request for communication in one of the selected cells C1-C3 is received by the mobile services switching center MSC1, and the mobile services switching center MSC1 includes receiving means 440, 441 for receiving A request for communication in a selected cell C1 of the at least one cell C1, C2. The selected cell may be, for example, cell C1.

In step 511, the mobile services switching center MSC1 determines whether the set of frequencies allocated for use in the selected cell C1 is sufficient to serve the request for communication.

If it is determined that the set of frequencies is sufficient (alternative "Yes"), it is checked in step 512 whether there is free capacity on the frequencies already in use, ie, whether there are time slots available for use. If there are available time slots on the frequency already in use (alternative "Yes"), then at step 513, the available time slots are allocated to service the communication request. If there are several allocated frequencies on which time slots are available, the mobile services switching center MSC1 tries to allocate a time slot on one of the basic frequency groups before allocating a time slot on one of the additional frequency groups. time slot.

If it is determined at step 512 that there are no available time slots on the frequency already in use (alternative "No"), then a new frequency is brought into use. Therefore, in step 514, a frequency allocated to cell C1 but not in use is selected, in step 515, the selected frequency is registered as in use, and in step 516, a time slot on the selected frequency is Allocated to service communication requests.

If it is determined in step 511 that the frequency group currently allocated to the cell C1 is not enough to serve the communication request ("No" of the two alternatives), then the mobile services switching center MSC1 enters into step 517 to determine that it is allocated for Candidate frequency groups of the cellular network 101 that are not currently used for communication in the vicinity of the cell C1. In the first embodiment of the invention, it is sufficient to include one candidate frequency in the set of candidate frequencies. In step 517, the mobile services switching center MSC1 uses the configuration data stored in the memory unit 441 to determine which cells are in the vicinity of the cell C1, and to check the registration status of the frequencies, i.e., which cells are active in said cells. The frequency used for communication or not used for communication is registered in the memory unit 441 . The process of finding candidate frequencies is performed in two steps. First, among the frequencies belonging to the basic frequency group assigned to the cell immediately adjacent to the cell C1 and preferably to one of the other cells C2-C3 served by the first base station (BS1) are identified potential candidate frequencies. Potential candidate frequencies are then checked at a distance from cell C1 corresponding to the reuse distance (i.e., between two base frequency groups allocated to the same basic frequency group according to the adopted "4/12" cell reuse pattern). is not in use in any cell within the distance between cells). In this way, it is ensured that no significant additional co-channel interference is introduced in the cellular network 101 when the candidate frequency is temporarily allocated for use in the cell C1.

In step 518, the mobile services switching center MSC1 borrows (ie temporarily allocates) the candidate frequency as an additional frequency for use in the cell C1. In order to accomplish this temporary allocation of candidate frequencies to cell C1, candidate frequencies are temporarily de-allocated, ie marked as unavailable, in neighboring cells of cell C1. In this way, as long as the candidate frequency is allocated to cell C1, it is no longer used for communication in cells in the vicinity of cell C1.

At step 519, time slots on nearby frequencies are allocated to service the communication request.

Figure 5C shows a series of steps performed when a communication session is complete.

In step 530 of Fig. 5C the time slot is released and in step 531 it is checked whether the released time slot is the last time slot used on the radio frequency carrier. If the time slot is not the last time slot (alternative "No"), ie, the RF carrier is still actively used for communication, then at step 532, the time slot is marked as available. If at step 531 the time slot is indeed determined to be the last time slot (alternative "Yes"), then at step 533 it is checked whether the RF carrier is an additional frequency to be allocated only temporarily to cell C1. If the RF carrier is not an additional frequency (alternative "NO"), then at step 534, the RF carrier is registered as inactive. If the radio frequency carrier frequency is actually an additional frequency, then at step 535, the carrier frequency is de-allocated from cell C1, i.e., the frequency is re-made available in those cells in the vicinity of cell C1, where the frequency is part of the basic set of frequencies allocated to those cells.

In another way of carrying out de-allocation of temporarily allocated additional frequencies in cell C1, it is checked at each time slot release whether there is sufficient capacity in the basic frequency group in the cell to handle ongoing communication sessions, if If yes, the communication session is moved from the additional frequency to a frequency in the base frequency set, and the additional frequency is deallocated.

In addition to the exemplary first embodiment of the present invention described above, several rearrangements, modifications and substitutions of the first embodiment may be provided, resulting in further embodiments of the present invention.

There are several alternative ways of implementing the power amplification unit of the first base station BS1 other than the specific embodiments disclosed in FIGS. 4 and 7 . Examples of other ways of arranging the power amplification unit can be found, for example, in US Patent 5,854,611 and US Patent 4,618,813.

Instead of each individual cell being served by the first base station BS1 using a single antenna beam, as shown in Figure 4, several narrow antenna beams may be used to serve each individual cell. In this embodiment of the invention, the first and second sets of radio signals comprise not just one but several radio signals associated with each respective cell. For each narrow antenna beam there is a low power radio signal from the first set of radio signals and a corresponding amplified radio signal from the second set of radio signals.

Instead of serving three cells C1-C3, the first base station BS1 is adjusted to serve only two cells or to serve more than three cells. Furthermore, the first base station BS1 may be adapted to serve cells arranged in a hierarchical cell structure, e.g. by serving additional umbrella cells thereby providing radio coverage in the area of at least one of the overlapping cells C1-C3 .

In the first embodiment of the invention, the mobile services switching center MSC1 and in particular the control processor 440 and the memory unit 441 can perform a number of different tasks and in particular can be used as:

- control means for controlling the radio frequency carrier component group comprised by the radio signal generating means 401 in each signal in the first group of radio signals S11-S13; wherein the control means 440, 441 are used to instruct the radio signal generating means 401 The first radio signal S11 is generated so as to contain a radio frequency carrier component having a frequency allocated for use in the first cell C1 of the cellular radio communication network 101, and said antenna system 403 is used to direct the antenna beam associated with the first cell C1 417 to radiate the amplified wireless signal S21 corresponding to the first wireless signal S11,

It is characterized in that the control means 440, 441 are used to instruct the wireless signal generating means 401 to generate the second wireless signal S12, so as to include a radio frequency carrier component having a frequency allocated to use in the second cell C2 of the cellular wireless communication network 101, and Said antenna system 403 is adapted to radiate an amplified radio signal S22 corresponding to the second radio signal S12 in the form of an antenna beam 418 associated with the second cell C2.

- adaptive means 440, 441 for adjusting the use in at least one cell allocated to said first and second cells C1, C2 in response to a predicted or actual change in capacity requirements in said at least one cell frequency group;

Said adaptation means 440, 441 are used to determine whether the current set of frequencies allocated for use in the selected cell C1 is sufficient to serve the request for communication, and if the current set of frequencies is insufficient, to allocate at least one The additional frequency is used in the selected cell C1;

Said adaptive means 440, 441 are used to determine a candidate frequency group comprising at least one frequency that is allocated for use in the terrestrial cellular radio communication network 101 but is not currently used for communication in the vicinity of the selected cell C1, and selecting at least one additional frequency from the set of candidate frequencies;

Said adaptation means 440, 441 are used to select at least one additional frequency as a frequency measured by the measuring means BS1 and determined to be subject to interference below a predetermined level.

- registration means for registering those frequencies which are currently actively used for communication.

Of course, some of these tasks could alternatively be performed in a base station controller (BSC) or some other kind of radio network controller (RNC) in a terrestrial cellular network.

With the present invention, it is possible to apply any power reduction function in the downlink direction to achieve a statistical reduction of the required total output power transmitted by the base station. Of course, it is possible to apply several different power reduction functions in combination to achieve even greater statistical reductions. Therefore, when implementing the invention in a GSM terrestrial cellular network, downlink power control and discontinuous transmission according to the GSM specification can and preferably should be used. Of course, it is also conceivable to add some downlink discontinuous transmission scheme to future revisions of the TIA/EIA IS-136 specification, for example based on the uplink transmissions currently specified in TIA/EIA IS-136. discontinuous transmission scheme, and it is also conceivable to modify the first embodiment of the invention described above in order to apply and benefit from the combined use of downlink power control and discontinuous transmission.

In the first embodiment of the present invention, whenever the required output power from the power amplifying unit 402 in a time slot exceeds the power amplifying capacity of the power amplifying unit 402, the power amplifying unit 402 will not be able to provide sufficient output power To transmit in bursts on an RF carrier for all operations on a time slot.

One way to handle situations where the power amplifying unit 402 fails to deliver sufficient output power is to refrain from transmitting bursts on one or a few active RF carriers in order to ensure that the power amplifying capability of the power amplifying unit 402 is not exceeded. The carriers on which bursts are not transmitted may be chosen randomly.

Another way to handle these situations is to transmit bursts on all active radio frequency carriers, but only on one or a few radio frequency carriers with less power, so as to ensure that the power amplification capability of the power amplification unit 402 is not exceeded . For example, the transmit power may be reduced equally on all active radio frequency carriers. If the transmission power on certain radio frequency carriers can be increased by reducing the transmission power on all active radio frequency carriers, the transmission power of the carrier with the lowest transmission power is increased first. Alternatively, instead of reducing the transmit power on all active radio frequency carriers, the strongest radio frequency carrier may be reduced in transmit power first.

The adaptive channel allocation scheme used in the first embodiment of the present invention is just one example of many different ACA schemes that can be used in the present invention.

Instead of selecting additional frequencies for allocation in the selected cell based on the mobile services switching center's knowledge of which frequencies are actually being used for communication in cells near the selected cell, the selection may be based on Measurements of interference levels in the selected cell on frequencies not currently assigned to the selected cell are performed. In this scheme, the additional frequency selected to be allocated to the cell is a measured frequency that is determined to experience interference below a predetermined level, and is included in the terrestrial cellular wireless communication network (101) using the present invention Measuring means for measuring, in the selected cell C1, an interference level on a frequency group not currently allocated to the selected cell C1. The measurement may be initiated after a request for communication is received in the selected cell, when it is detected that the set of frequencies allocated for use in the selected cell is insufficient to serve the request for communication. However, in order not to introduce unnecessary delays in processing requests for communication, it is preferable to perform interference level measurements continuously. This measurement can be performed by a scanning receiver in the base station serving the selected cell, as proposed in published international patent application WO 97/32444.

As will be apparent to those skilled in the art, the application of the present invention is by no means limited to terrestrial cellular communication networks complying with the EIA/TIA IS-136 specification. Thus, the invention is also applicable to GSM-, PDC, AMPS, TACS, NMT, or IS-95 specifications and developments of these specifications (such as EDGE or GPRS) as long as the cellular network includes base stations serving several cells. cellular network.

Claims (25)

1. A terrestrial cellular wireless communication network (101) comprising at least a first base station (BS1), the first base station (BS1) comprising: A wireless signal generating device (401), configured to generate a first group of low-power wireless signals (S11-S13), including at least a first wireless signal (S11) and a second wireless signal (S12); a power amplifying unit (402), configured to amplify the first set of wireless signals by using a common set of multi-carrier power amplifiers (409-412) to generate a second set of amplified wireless signals corresponding to the first set of wireless signals (S11-S13) signal(S21-S23); an antenna system (403) for radiating a second set of amplified wireless signals (S21-S23) in the form of associated antenna beams (417-419); The cellular wireless communication network (101) also includes: control means (440, 441) for controlling the set of radio frequency carrier components generated by the radio signal generating means (401) included in each of the first set of radio signals (S11-S13), Wherein the control means (440, 441) is used to instruct the radio signal generating means (401) to generate the first radio signal (S11) so as to contain the radio signals allocated for use in the first cell (C1) of the cellular radio communication network (101) A radio frequency carrier component of a frequency, and said antenna system (403) is used to radiate an amplified radio signal (S21) corresponding to the first radio signal (S11) in the form of an antenna beam (417) associated with the first cell (C1) ), It is characterized in that the control device (440, 441) is used to instruct the wireless signal generating device (401) to generate the second wireless signal (S12) so as to include the second cell (C2) with the distribution in the cellular wireless communication network (101) The radio frequency carrier component of the frequency used in and said antenna system (403) is used to radiate the amplified radio signal (S12) corresponding to the second radio signal (S12) in the form of an antenna beam (418) related to the second cell (C2). signal (S22). 2. According to the terrestrial cellular wireless communication network (101) of claim 1, wherein the power amplification unit (402), in addition to the multi-carrier power amplifier (409-412) of the public group, also includes a power sharing network (408) and a reverse The power sharing network (413), the power sharing network (408) and the reverse power sharing network (413) both have a plurality of input and output ports (420-435), in a common set of multi-carrier power amplifiers (409-412) Each of the amplifiers in has an input port connected to an output port of the power sharing network (408), and has an output port connected to an input port of the reverse power sharing network (413), The power sharing network (408) is configured to receive the first set of radio signals (S11-S13) at its input ports (420-422) and distribute some portion of each signal (S11-S13) of the first set of radio signals to each of its output ports (424-427), thereby providing a third group of wireless signals (S31-S34) at its output ports (424-427), The common set of multi-carrier power amplifiers (409-412) is used to provide a fourth set of radio signals ( S41-S44), The reverse power sharing network (413) is used to receive the fourth group of wireless signals (S41-S44) at its input ports (428-431) and perform the reverse operation of the power sharing network (408), thereby in its A second set of wireless signals (S21-S23) is provided at the output ports (432-434). 3. The terrestrial cellular wireless communication network (101) according to claim 2, wherein the power sharing network (408) is used to divide each signal in the first group of wireless signals (S11-S13) at almost equal power levels assigned to each of its output ports (424-427). 4. The terrestrial cellular wireless communication network (101) according to any one of claims 2-3, wherein the power sharing network (408) is used to stagger the phases of the first group of wireless signals (S11-S13) Portions of the signal are distributed to each of its output ports (424-427). 5. The terrestrial cellular wireless communication network (101) according to any one of claims 1-3, wherein the power amplifying unit (402) is configured to perform a power transmission in a service provided by the first base station (BS1), including at least the first cell (C1) and the power amplification of all radio frequency carriers transmitted on the downlink in a group of cells (C1-C3) of the second cell (C2), and the cellular radio communication network (101) is used to apply the power reduction function To the transmission in the downlink direction of the cell group (C1-C3). 6. The terrestrial cellular radio communication network (101) according to any one of claims 1-3, wherein the cellular radio communication network comprises: Adaptive means (440, 441) for adjusting at least one cell allocated in said first and second cells (C1, C2) in response to predicted or actual changes in capacity requirements in said at least one cell. The frequency group used in the cell. 7. The terrestrial cellular wireless communication network (101) according to claim 6, wherein the cellular wireless communication network (101) further comprises: receiving means (440, 441) for receiving a request for communication in a selected cell (C1) of said at least one cell (C1, C2), said adapting means (440, 441) for determining whether the current set of frequencies allocated for use in the selected cell (C1) is sufficient to serve the request for communication, and if the current set of frequencies is insufficient, At least one additional frequency is then allocated for use in the selected cell (C1). 8. The terrestrial cellular radio communication network (101) according to claim 7, wherein the cellular radio communication network (101) comprises: registration means (440, 441) for registering those frequencies that are currently actively used for communication in the vicinity of the selected cell (C1), Said adaptive means (440, 441) are configured to determine at least one frequency allocated for use in the terrestrial cellular radio communication network (101) but not currently used for communication in the vicinity of the selected cell (C1) The candidate frequency set, and at least one additional frequency is selected from the candidate frequency set. 9. The terrestrial cellular radio communication network (101) according to claim 7, wherein the cellular radio communication network comprises: measuring means for measuring, in the selected cell (C1), the interference level on a frequency group not currently allocated to the selected cell (C1), and Said adapting means (440, 441) are adapted to select at least one additional frequency as a frequency measured by the measuring means (BS1) and determined to be subject to interference below a predetermined level. 10. A terrestrial cellular radio communication network (101) according to claim 9, wherein the measuring means are adapted to continuously measure the interference level in the selected cell (C1). 11. The terrestrial cellular radio communication network (101) according to any one of claims 1-3, wherein the cellular radio communication network (101) comprises a Mobile Services Switching Center (MSC1) to which said first base station (BS1) is connected , the switching center includes control means (440, 441). 12. A terrestrial cellular radio communication network (101) according to claim 9, wherein the first base station (BS1) comprises measuring means. 13. A method for transmitting a wireless signal (S21-S23) in a terrestrial cellular wireless communication network (101) comprising at least a first base station (BS1), the method comprising the following steps performed in the first base station (BS1): (a) generating (501) a first set of low-power wireless signals (S11-S13), including at least a first wireless signal (S11) and a second wireless signal (S12); (b) amplifying the first set of radio signals by using a common set of multicarrier power amplifiers (409-412), thereby generating (502-504) a second set of amplified radio signals corresponding to the first set of radio signals (S11-S13) signal(S21-S23); (c) radiating (505) the second set of amplified wireless signals (S21-S23) in the form of associated antenna beams (417-419); wherein a first radio signal (S11) is generated so as to contain a radio frequency carrier component having a frequency allocated for use in a first cell (C1) of a cellular radio communication network (101), and with a frequency associated with the first cell (C1) radiating the amplified wireless signal (S21) corresponding to the first wireless signal (S11) in the form of an antenna beam (417), It is characterized in that the second wireless signal (S12) is generated so as to contain a radio frequency carrier component having a frequency allocated to use in a second cell (C2) of the cellular wireless communication network (101), and to communicate with the second cell (C2) ) to radiate the amplified wireless signal (S22) corresponding to the second wireless signal (S12) in the form of an associated antenna beam (418). 14. The method according to claim 13, wherein the generating step (b) comprises the substeps of: (d) providing (502) a third set of radio signals ( S31-S34); (e) providing (503) a fourth set of radio signals (S41-S44) by amplifying each of the signals of the third set of radio signals (S31-S34) in one of the multi-carrier power amplifiers (409-412); (f) Providing (504) a second set of wireless signals by performing the reverse operation of step (d) on the fourth set of wireless signals (S41-S44). 15. A method according to claim 14, wherein each signal of the first set of radio signals (S11-S13) is divided into parts having substantially equal power levels. 16. A method according to any one of claims 14 or 15, wherein each signal of the first set of radio signals (S11-S13) is distributed with a staggered phase. 17. A method according to any one of claims 13-15, wherein the terrestrial cellular radio communication network (101) applies a power reduction function to services provided by the first base station (BS1), including at least the first cell (C1 ) and the transmission in the downlink direction of the group of cells (C1-C3) of the second cell (C2). 18. A method according to any one of claims 13-15, wherein the method further comprises the step of: (g) an adjustment (511-518) is allocated in at least one of said first and second cells (C1, C2) in response to a predicted or actual change in capacity requirements in said at least one cell The frequency group to use. 19. The method according to claim 18, wherein step (g) comprises the following substeps: (h) receiving (510) a request for communication in a cell (C1) selected from said at least one cell (C1, C2); (i) determining (511) that the current set of frequencies allocated for use in the selected cell (C1) is insufficient to serve the request for communication; (j) allocating (518) at least one additional frequency for use in the selected cell (C1). 20. The method according to claim 19, wherein step (g) comprises the substeps of: (k) registering (515, 532) those frequencies currently being used for communication in the vicinity of the selected cell (C1); (l) determining (517) a candidate frequency group comprising at least one frequency that is allocated for use in the terrestrial cellular radio communication network (101) but is not currently used for communication in the vicinity of the selected cell (C1), wherein the at least one additional frequency allocated in step (j) is selected from the candidate set. 21. The method according to claim 19, wherein step (g) further comprises the steps of: (m) measuring the interference level in the selected cell (C1) on frequency groups not currently allocated to the selected cell (C1), Wherein the at least one additional frequency allocated in step (j) is a frequency measured in step (m) and determined to experience interference below a predetermined level. 22. The method according to claim 21, wherein the measuring step (m) is performed continuously. 23. A method according to claim 21, wherein the measuring step (m) is initiated after step (h) receives a request for communication. 24. in the first base station (BS1) according to the terrestrial cellular wireless communication network (101) of claim 5, determine the method for the scale of power amplifying unit (402), this method comprises the following steps: (a) determining (801) a statistical allocation (901) of the total output power of the power amplification unit (402) required to simultaneously transmit up to a specified maximum number of radio frequency carriers in the group of cells (C1-C2); (b) sizing (802) the power amplification unit (402) based on the statistical distribution (901) determined in step (a). 25. The method according to claim 24, wherein the power amplification unit (402) is dimensioned in step (b) so that it can deliver a total maximum output power that provides an acceptable non-zero probability, the probability refers to the situation that the power amplifying unit (402) cannot provide enough output power to simultaneously transmit the specified maximum number of radio frequency carriers.

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